Morning woes

Last couple of mornings, my DTR-2100 has started struggling to get going. Don't we all.

The audio is fine (proving I'm receiving a signal), the on-screen Guide & Menu is fine (proving there's nothing wrong with the HDMI from PVR to TV, but the broadcast video itself is just black nothingness. Powering off/on at the mains recovers normal operation.

One thing I haven't tried in the failing state is to play back a recording ... I'll try that tomorrow if it happens again.

I notice in the menu that the box is set to go into deep sleep (or whatever the term is) overnight, so I'm wondering if it's somehow not recovering from this. SW version is 31.28.0.

Any ideas, or is my box about to die on me? I knew it was a mistake to stop the monthly payments to BT ;-)